refactor: replace wildcard imports with explicit imports (docker/mod.rs)

Per Rust API guidelines C-IMPORT, explicit imports make it clear
what's actually used from each module.

src/docker/mod.rs

@@ -2,9 +2,9 @@ use anyhow::{Context, Result};
 use tokio::time::{Duration, sleep};
 use tracing::info;
 
-use crate::config::*;
+use crate::config::{Cluster, Config, NcclConfig, Node, Recipe, load_recipe, resolve_cluster};
 use crate::doctor::try_repaired_image;
-use crate::ssh::*;
+use crate::ssh::{run_ssh, run_ssh_follow, run_ssh_with_retry};
 /// Launches containers across the cluster for a recipe.
 pub async fn serve(
     config: &Config,